The overall objective is to identify and describe, at a fundamental level, the biological mechanisms relating bacterial products in plaque and gingival debris to alveolar bone resorption in periodontal disease. Primarily a bone tissue culture model using chemically-defined media will be used. Bone resorption will be assessed quantitatively by the release of previously incorporated 45Ca from paired test and control bones from 19 day old fetal rats. We also are attempting to develop a monkey model for periodontitis using 125I absorptiometry as a highly sensitive and nondestructive technique to assess alveolar bone loss. BIBLIOGRAPHIC REFERENCES: Gomes, B.C., Hausmann, E., Weinfeld, N. and DeLuca, C. Prostaglandins: Bone Resorption Stimulating Factors Released from Monkey Gingiva. Calc. Tiss. Res. 19: 285-293, 1976. Rowe, D.J. and Hausmann, E. The Alteration of Osteoclast Morphology by Diphosphonates in Bone Organ Culture. Calc. Tiss. Res., 20: 53-60, 1976.